1. Field of the invention
The present invention relates to a structure of a coil bobbin for use of a magnetic head core of a floating type of magnetic head to be used for a magnetic disc.
2. Prior Art
Conventionally, as a known example of a floating type of magnetic head for use of a magnetic disc apparatus, there has been, as shown in FIG. 8, a composite type of magnetic head. In this magnetic head, a slit 2 is formed on an end of a slider 1, and a magnetic head core 3 is inserted in said slit 2 and bonded to the slider 1 using a glass 4.
Recently, there has been a tendency of the magnetic disc apparatus to be improved in response to the demand of the increase of recording density and to make the data transfer rate fast, for that purpose, the magnetic head is required to increase the resonance frequency, while the inductance of the magnetic head core is needed to be reduced.
In order to reduce the inductance of the magnetic head core, except changing a number of coil turns, it is attained by the following change of configuration of a magnetic head core, i.e. (1) to shorten the length of magnetic path, and (2) to make the thickness of the magnetic core thin.
However, when trying to realize such structure of magnetic head core, it can not be avoided to make the configuration of said magnetic head core smaller and thinner. Accordingly, in a trial for realizing such composite type of magnetic head core as shown in FIG. 8, it has been difficult to realize such head core because of handling difficulties, poor workability and easy breakage.
On the contrary, as a magnetic head which can use a magnetic head core having lowered inductance value, there is a floating magnetic head shown in FIG. 9. This floating magnetic head is formed by installing a magnetic head core 3 on the side of the slider 1 in such a manner as bridging a window 5 which is provided on an end of the slider 1.
This magnetic head core 3 is formed by bonding C-shaped first and second cores 6 and 7, and on one of bonding portions a gap 8 is provided. On legs 9 and 10 of said first and second cores 6 and 7, coils 11 and 12 are wound respectively, wherein said windings are made in a so-called balanced manner so as to cancel noise from outside.
However, in this type of floating magnetic head, the coils 11 and 12 are wound directly around the legs 9 and 10, so that such coils have been apt to be damaged by the corners of the legs 9,10 in the form of cutting or insulation malfunctioning due to the peeling of coil-coatings.
In order to prevent such cutting of coils and malfunction of insulation, it is considered to wind coils on a magnetic head core through a coil bobbin attached to the magnetic head core. One example as such is shown in FIG. 10, wherein a bobbin consists of a body 14 having a C shape in section, both ends 16 of which function as a hook, a pair of flanges 15 formed on both ends of said body 14 in unitary manner with said hooks 16,16 having slopes 18 inclined toward an opening 17 of the bobbin. These slopes 18 function to open the opening 17 wider when the coil bobbin 13 is installed on a core. The hooks 16 of the coil bobbin 13 are hooked on a leg of C-shaped core not shown to prevent it from removing.
Further, another example of such coil bobbin is illustrated in FIG. 11, wherein said bobbin is formed with a pair of opposing plate-like arms 20, 20, one side edges of those arms are connected by a back plate 21 to form a frame 22 having U-letter shape in section. From opposing plate-like arms 20, 20 hooking plates 23, 23 are projected toward the opening of the frame 22. And, the plate-like arms 20 and the back plate 21 surround a leg of C-type core not shown, and the hooking plates 23, 23 function as a stopper for securing the bobbin on the core.
Now, upon using the above mentioned bobbins of FIGS. 10 or 11 in the floating magnetic head shown in FIG. 9, two bobbins 13 are needed, which causes an extra mounting process. And, when pushing a bobbin 13 against a core for installing, there is an anxiety of damaging the corners of the core, on which a coil bobbin 13 is pushed, because two hooks are projected in such a manner as reducing the spacing of the opening 17.
The present invention has been made in the light of the above problems, in which a bobbin for use of a magnetic head core, on one hand prevents cutting of coils to be wound and malfunctioning of insulation, and on the other hand increases mounting workability and enables to wind coils in balance manner.